Since biomass sorghum hybrids are photoperiod sensitive, seed production relies on either genetic control of photoperiod sensitivity or strategic planting in seed production environ­ments. In the latter, day length during winter months in tropical environments is sufficiently short to allow seed production of hybrids. In this situation, the greatest challenge is planting seed and pollinator seed stock in time to ensure both reach anthesis at the same time. In temperate environments, such production is not possible because of cool temperatures dur­ing the winter season. Therefore, seed production must rely on genetic systems that allow production of a photoperiod sensitive hybrid using two photoperiod sensitive parental lines. Such a system was identified and characterized in forage sorghums [47, 65] and can be readily deployed within a bioenergy breeding program.

Breeding for biomass production uses approaches similar to those currently used to produce hybrid forage sorghum. Vegetative biomass yield will be the most important trait, as is the case with current forage types. In most cases, biomass sorghum cultivars are being bred for a single harvest management scheme. Although multiple cut types could be used, they most likely will be forage types, as those perform very well in multiple-cut production systems [91]. Inbred line development will follow the same approaches used for grain and forage sorghum. For energy sorghums, most of the breeding effort will focus on the pollinator parent because existing seed parent lines are suitable for use to produce biomass sorghum hybrids. Potential pollinator parents range from existing elite sorghum germplasm with good general combining ability to unique genotypes that maximize photoperiod sensitivity and are derived from exotic sorghum accessions. Initial screening for maturity, yield, composition and agronomic desirability will be used to identify pollinator parents, which can be improved through further breeding to complement existing seed parents for both maturity and dwarfing loci. This will allow for the production of hybrids using lines that are moderately short and photoperiod insensitive but that produce a hybrid that is tall and photoperiod sensitive [26, 47].